1. Field of the Invention
The present invention relates to control systems and more particularly to an automatic elevator control system.
2. Description of Prior Art
Older vesions of shipboard elevator control systems use large relays coupled with generally unreliable mechanical limit switches. More recent control systems use proximity switches with solid state logic controllers. While the old systems have reliability problems, the newer systems are difficult to troubleshoot and repair parts are expensive and difficult to obtain. In addition, there is a need for additional safety and automatic control features not presently available. In particular, two safety problems with existing systems are: (1) in a system with a two-speed motor controller, the failure of a stop switch in the elevator trunk often results in the controller commanding the high-speed contactor to pull in when the platform destination has been passed and the elevator is in a portion of the trunk not covered by leveling sensors, and (2) upon the failure of a platform sensing switch, existing elevator platform logic circuitry frequently will stop the platform at the extreme of travel in the direction of the dispatch, but not immediately at intermediate levels when the failure is recognized. Additionally, the open elevator trunk of existing systems poses a fire hazard.